Biomedical subjects

Roberto Argazzi

Publications and source records attributed to Roberto Argazzi.

7 recordsLinked to original sources

PubMed2006

Efficient non-corrosive electron-transfer mediator mixtures for dye-sensitized solar cells.

The electrochemical and photoelectrochemical study of noncorrosive electron-transfer mediator mixtures for DSC is reported. These mixtures, characterized by the presence of kinetically fast organic or metal-organic redox couples in conjunction with a Co(II)/(III) relay, exhibited maximum photon-to-current conversion efficiencies (IPCE %) exceeding 80% when employed in the presence of a suitably designed MLCT sensitizer, rivaling with the performances of the classical I-/I3- electrolyte.

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PubMed2006

6-N,N-dimethylamino-2,3-naphthalimide: a new environment-sensitive fluorescent probe in delta- and mu-selective opioid peptides.

A new environment-sensitive fluorophore, 6-N,N-(dimethylamino)-2,3-naphthalimide (6DMN) was introduced in the delta-selective opioid peptide agonist H-Dmt-Tic-Glu-NH(2) and in the mu-selective opioid peptide agonist endomorphin-2 (H-Tyr-Pro-Phe-Phe-NH(2)). Environment-sensitive fluorophores are a special class of chromophores that generally exhibit a low quantum yield in aqueous solution but become highly fluorescent in nonpolar solvents or when bound to hydrophobic sites in proteins or membranes. New fluorescent delta-selective irreversible antagonists (H-Dmt-Tic-Glu-NH-(CH(2))(5)-CO-Dap(6DMN)-NH(2) (1) and H-Dmt-Tic-Glu-Dap(6DMN)-NH(2) (2)) were identified as potential fluorescent probes showing good properties for use in studies of distribution and internalization of delta receptors by confocal laser scanning microscopy.

Animals↗

PubMed2005

Solid-state photochromic device based on nanocrystalline TiO2 functionalized with electron donor-acceptor species.

In this Communication, we report on a new type of solid-state photochromic device, S-TiO(2)-A, which is based on electron-transfer processes involving a molecular sensitizer (S) and an electron acceptor (A) coadsorbed onto the surface of nanocrystalline TiO(2). The electron-transfer process is mediated by the semiconductor conduction band and leads to a long-lived charge-separated state S(+)/A(-). The lifetime of this state can be controlled by oxygen diffusion through a polymeric coating deposited on the device.

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PubMed2005

Sensitization of nanocrystalline TiO2 with black absorbers based on Os and Ru polypyridine complexes.

New metal complexes of the type [M(H3tcterpy)LY]+ (where M = Os(II) or Ru(II), L = substituted or unsubstituted bipyridine or pyridylquinoline, and Y = Cl-, I-, or SCN-) have been designed, synthesized, and characterized in view of their application for dye-sensitized solar cells (DSSCs). The Os dyes show a very broad absorption, and correspondingly, the DSSCs show an unprecedented spectral response in the NIR, with an onset at 1100 nm, reaching values of about 50% at 900 nm. The integrated photocurrent of some of such Os dyes is similar to that of the well-known [Ru(Htcterpy)(NCS)3](TBA) and superior to that of the [Ru(Hdcbpy)2(NCS)2](TBA)2 sensitizer. The Ru dyes show absorption and DSSC spectral response between those of the red and black dyes. Their advantage is their potential superior stability due to the reversible oxidative electrochemistry.

Journal Article↗

PubMed2004

Highly selective fluorescent analogue of the potent delta-opioid receptor antagonist Dmt-Tic.

A fluorescent tripeptide probe derived by coupling fluorescein to H-Dmt-Tic-Glu-NH2 was developed to interact with delta-opioid receptors with high affinity (Ki = 0.035 nM) and selectivity (Ki(mu)/Ki(delta) = 4371). It acts as an irreversible delta-opioid receptor antagonist, and binding to NG108-15 cells is blocked by the standard nonpeptidic delta-opioid receptor antagonist naltrindole. This probe should prove useful in the study of the distribution of delta-opioid receptors in tissues and the internalization of opioid peptides during signal transduction.

Animals↗

PubMed2003

Electrochromic devices based on binuclear mixed valence compounds adsorbed on nanocrystalline semiconductors.

A series of cyano-bridged binuclear mixed valence complexes of the general formula M-Ru(III)(NH(3))(4)pyCOOH [pyCOOH = isonicotinic acid; M = cis-Ru(bpy)(2)(CN)(2), 1 (bpy = 2,2' bipyridine); trans-Ru(py)(4)(CN)(2), 2 (py = pyridine); [Ru(CN)(6)](4)(-), 3; [Fe(CN)(6)](4)(-), 4] have been prepared and anchored through the carboxylic function to nanocrystalline TiO(2) or SnO(2) electrodes. The complexes display a reversible electrochromic behavior in the range of applied potential from -0.5 to +0.5 V, versus SCE. Tuning of the electronic transitions in the visible and near-infrared spectral regions is achieved through changes of the solvent and of the cyano-bridged metal moiety M.

Journal Article↗

PubMed1998

Efficient Light-to-Electrical Energy Conversion with Dithiocarbamate-Ruthenium Polypyridyl Sensitizers.

New Ru(dcbH)(dcbH(2))(L) sensitizers, where L is diethyldithiocarbamate, dibenzyldithiocarbamate, or pyrrolidinedithiocarbamate, dcbH is 4-(COOH)-4'-(COO(-))-2,2'-bipyridine, and dcbH(2) is 4,4'-(COOH)(2)-2,2'-bipyridine, have been synthesized, characterized, and anchored to nanocrystalline TiO(2) films for light to electrical energy conversion in regenerative photoelectrochemical cells with I(-)/I(2) acetonitrile electrolyte. The sensitizers have intense metal-to-ligand charge-transfer (MLCT) bands centered approximately 380 and 535 nm that sensitize TiO(2) over a notably broad spectral range. The photophysical and photoelectrochemical studies of these materials are contrasted with cis-Ru(dcbH(2))(2)(NCS)(2), which is one of the most efficient sensitizers reported to date. Photophysical measurements show that the high photocurrent observed for cis-Ru(dcb)(2)(NCS)(2)/TiO(2) is due to efficient and rapid iodide oxidation.

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